The present invention relates to a thermally shrinkable film having a liquid detecting function and a package using the same and, more particularly, to a thermally shrinkable film with a liquid detecting function and a package of an item or object or of a container filled with a liquid or packaged dry material. The thermally shrinkable film is adapted for use with a paper pack container or a plastic container in which a liquid material is to be filled, or with a glass container and the like in which an individual item is bundled or plural items are to be bundled, wrapped or packed. The thermally shrinkable film is particularly useful for thermoshrinkably bundling, wrapping or packing an items or objects containing a liquid, such as pickles or other goods, which in turn are bundled, wrapped or packed in a plastic container. The thermally shrinkable film is also useful for bundling, wrapping or packing an item or object necessary to be held in a dry state, such as dry foodstuff.
Furthermore, in accordance with the present invention, the package comprises an item or object to be packed or a container with the item or object packaged therein and the thermally shrinked film can be used for the purpose of detecting a liquid leaking from the packed item or object or the container or a liquid entering into the packed item or object through the thermally shrunk film. This liquid detecting function permits ensuring the integrity of items or objects such as juices, milk, coffee, bean milk, tea and the like, in vacuum packed paper pack containers and other containers. The thermoshrinkable film and the package according to the present invention also confirm a the extent of dryness of dry items or objects in containers and will identify the penetration of any liquid therethrough into containers from the outside.
Heretofore, when an item or object or a container with the item or object packed is thermoshrinkably packaged with a conventional thermally shrinkable film, leakage of a liquid and entry thereof can be easily detected if a considerably large amount of a liquid from a packaged material or a package or penetrates to the inside of the packaged material. However, it has been extremely difficult or even impossible to detect the leakage of a small amount of a liquid from a container using a conventional thermoshrinkable film or the penetration of a small amount of liquid through the package. This situation is all the more difficult if a liquid is colorless or transparent.
Furthermore, in instances where paper pack containers in which foodstuff and other items are packed by vacuum packaging are further packed thermoshrinkably by a conventional thermoshrinkable plastic film, it is virtually impossible for consumers and sellers to check whether the containers are held in a substantially vacuum state before opening the containers. Even if a small hole exists in a container through which air may penetrate into the container and the contents in the container would decay or rot, or even if a poisonous or hazardous substance is intentionally inserted, using an injector's needle, through the container, such a small amount of a foreign substance could not be detected.
On top of that, in the case of dry items or objects packed in a conventional thermoshrinkable film, it has been practially impossible for consumers and sellers to check before opening whether the dry items have been maintained in a sufficient degree of dryness while being packed in a container.